Professor Douglas Davies, a professor in the study of religion at Durham University, said young people were scared of the emotional impact of bereavement and warned that a modern "avoidance of being upset" could stop people grieving properly.

He said they lived in a "safety world" which shielded them from the impact of negative emotions.

"Think of all these youngsters who have been looked after from the time they're babies, driven to school, all that sort of stuff.

"Death is a bit of a shock when your mother's been really looking after you for years," he said.

He suggested that young people's prolific use of social media increased the level of "living input" they experienced and made it harder and more painful to think about death.

"The more information we get into our system, the more we are getting used to being around," he said, suggesting that an acute "fear of missing out" made it painful to consider "the thought of there being nothing".

The practice of direct cremation, already common in America, has received greater public attention since the death of David Bowie in January 2016. He opted for the no-frills service and asked for his ashes to be scattered in Bali.

But Professor Davies said the emotional impact on mourners of opting for a no-frills funeral had not been fully researched.

"What concerns me there is the fact that our emotions take wave forms and go up and down. The more they go up and down, the more we look back on them and remember and experience the event.

"If you are removing the fluctuation you are possibly removing the richness of human experience, where it can be negative as well as positive," he warned.

He added that families opting for non-traditional forms of funeral such as using a civil celebrant or scattering ashes could end up feeling like they had not given their relative a "good send off".

In one case, a family who had used a civil celebrant had later decided to ask a priest to come and do another ceremony because they did not feel the person had been properly laid to rest.

He added that many of the cases where services involved direct cremations were likely to be elderly people with few close relatives left living.

Others would opt for the service because of its low cost, which can be thousands of pounds less than a standard funeral.

Royal London's report found that the average funeral in 2017 cost £3,784, a three per cent rise on the previous year.